libjava/java/util/natTimeZone.cc

   1 // natTimeZone.cc -- Native side of TimeZone class.
   2
   3 /* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 #include <config.h>
  12 #include <platform.h>
  13
  14 #include <gcj/cni.h>
  15 #include <jvm.h>
  16
  17 #include <java/util/TimeZone.h>
  18 #include <java/lang/Character.h>
  19 #include <java/lang/Integer.h>
  20
  21 #include <stdio.h>
  22
  23 #if TIME_WITH_SYS_TIME
  24 # include <sys/time.h>
  25 # include <time.h>
  26 #else
  27 # if HAVE_SYS_TIME_H
  28 #  include <sys/time.h>
  29 # else
  30 #  include <time.h>
  31 # endif
  32 #endif
  33
  34 #include <string.h>
  35
  36 /*
  37  * This method returns a time zone string that is used by init_properties
  38  * to set the default timezone property 'user.timezone'.  That value is
  39  * used by default as a key into the timezone table used by the
  40  * java::util::TimeZone class.
  41  */
  42 static jstring
  43 getSystemTimeZone (void)
  44 {
  45   struct tm *tim;
  46   time_t current_time;
  47   long tzoffset;
  48   const char *tz1, *tz2;
  49   char *tzid;
  50
  51   current_time = time(0);
  52
  53   mktime(tim = localtime(&current_time));
  54 #ifdef STRUCT_TM_HAS_GMTOFF
  55   // tm_gmtoff is secs EAST of UTC.
  56   tzoffset = -(tim->tm_gmtoff) + tim->tm_isdst * 3600L;
  57 #elif HAVE_UNDERSCORE_TIMEZONE
  58   tzoffset = _timezone;
  59 #elif HAVE_TIMEZONE
  60   // timezone is secs WEST of UTC.
  61   tzoffset = timezone;
  62 #else
  63   // FIXME: there must be another global if neither tm_gmtoff nor timezone
  64   // is available, esp. if tzname is valid.
  65   // Richard Earnshaw <rearnsha@arm.com> has suggested using difftime to
  66   // calculate between gmtime and localtime (and accounting for possible
  67   // daylight savings time) as an alternative.
  68   tzoffset = 0L;
  69 #endif
  70
  71 #ifdef HAVE_TM_ZONE
  72   tz1 = tim->tm_zone;
  73   tz2 = "";
  74 #elif defined (HAVE_TZNAME)
  75   tz1 = tzname[0];
  76   tz2 = strcmp (tzname[0], tzname[1]) ? tzname[1] : "";
  77 #else
  78   // Some targets have no concept of timezones.
  79   tz1 = "???";
  80   tz2 = tz1;
  81 #endif
  82
  83   if ((tzoffset % 3600) == 0)
  84     tzoffset = tzoffset / 3600;
  85
  86   tzid = (char*) _Jv_Malloc (strlen(tz1) + strlen(tz2) + 6);
  87   sprintf(tzid, "%s%ld%s", tz1, tzoffset, tz2);
  88   jstring retval = JvNewStringUTF (tzid);
  89   _Jv_Free (tzid);
  90
  91   return retval;
  92 }
  93
  94 // Get the System Timezone as reported by the OS.  It should be in
  95 // the form PST8PDT so we'll need to parse it and check that it's valid.
  96 // FIXME: Using the code from Classpath for generating the System
  97 // Timezone IMO is suboptimal because it ignores whether the rules for
  98 // DST match up.
  99 jstring
 100 java::util::TimeZone::getDefaultTimeZoneId ()
 101 {
 102   jstring sysTimeZoneId = getSystemTimeZone ();
 103
 104   using namespace java::lang;
 105
 106   // Check if this is a valid timezone.  Make sure the IDs match
 107   // since getTimeZone returns GMT if no match is found.
 108   TimeZone *tz = TimeZone::getTimeZone (sysTimeZoneId);
 109   if (tz->getID ()->equals (sysTimeZoneId))
 110     return sysTimeZoneId;
 111
 112   // Check if the base part of sysTimeZoneId is a valid timezone that
 113   // matches with daylight usage and rawOffset.  Make sure the IDs match
 114   // since getTimeZone returns GMT if no match is found.
 115   // First find start of GMT offset info and any Daylight zone name.
 116   int startGMToffset = 0;
 117   int sysTimeZoneIdLength = sysTimeZoneId->length();
 118   for (int i = 0; i < sysTimeZoneIdLength && startGMToffset == 0; i++)
 119     {
 120       if (Character::isDigit (sysTimeZoneId->charAt (i)))
 121         startGMToffset = i;
 122     }
 123
 124   int startDaylightZoneName = 0;
 125   jboolean usesDaylight = false;
 126   for (int i = sysTimeZoneIdLength - 1;
 127        i >= 0 && !Character::isDigit (sysTimeZoneId->charAt (i)); --i)
 128     {
 129       startDaylightZoneName = i;
 130     }
 131   if (startDaylightZoneName > 0)
 132     usesDaylight = true;
 133
 134   int GMToffset
 135     = Integer::parseInt (startDaylightZoneName == 0 ?
 136                          sysTimeZoneId->substring (startGMToffset) :
 137                          sysTimeZoneId->substring (startGMToffset,
 138                                                    startDaylightZoneName));
 139
 140   // Offset could be in hours or seconds.  Convert to millis.
 141   if (GMToffset < 24)
 142     GMToffset *= 60 * 60;
 143   GMToffset *= -1000;
 144
 145   jstring tzBasename = sysTimeZoneId->substring (0, startGMToffset);
 146   tz = TimeZone::getTimeZone (tzBasename);
 147   if (tz->getID ()->equals (tzBasename) && tz->getRawOffset () == GMToffset)
 148     {
 149       jboolean tzUsesDaylight = tz->useDaylightTime ();
 150       if (usesDaylight && tzUsesDaylight || !usesDaylight && !tzUsesDaylight)
 151         return tzBasename;
 152     }
 153
 154   // If no match, see if a valid timezone has the same attributes as this
 155   // and then use it instead.
 156   jstringArray IDs = TimeZone::getAvailableIDs (GMToffset);
 157   jstring *elts = elements (IDs);
 158   for (int i = 0; i < IDs->length; ++i)
 159     {
 160       // FIXME: The daylight savings rules may not match the rules
 161       // for the desired zone.
 162       jboolean IDusesDaylight =
 163         TimeZone::getTimeZone (elts[i])->useDaylightTime ();
 164       if (usesDaylight && IDusesDaylight || !usesDaylight && !IDusesDaylight)
 165         return elts[i];
 166     }
 167
 168   // If all else fails, return null.
 169   return NULL;
 170 }